Hammett's Planisphere showing the Principal Stars visible for every hour in the year from Lat. 40 degrees N. Heavy cardstock with rotating disc. Made by J.L. Hammett Company, in Great Britain, I believe this one was printed in the early 1900s. Helps you locate the stars and constellations. Excellent condition, slight wear and discoloration, rotates with ease. Measures 12 1/4".